The Cost of Shoreline Protection: A Comparison of Approaches in Coastal New England and the Mid-Atlantic

Abstract Shoreline hardening is a method of coastal hazard protection that is often implemented by government agencies and individual property owners. As awareness of the potential negative effects of shoreline hardening has increased, natural and nature-based approaches have gained in popularity. Most research related to shoreline protection has focused on understanding the environmental and ecological effects. However, for hybrid, nature-based approaches, in particular, there is limited information available to compare their monetary costs. To fill this gap, this study used information collected from public shoreline protection projects within the New England and Mid-Atlantic areas to estimate the costs of these measures based on the materials used, such as vegetation, sand, and/or stone. This approach allows for a detailed measurement of potential project inputs and provides needed cost information on the types of materials local governments and other stakeholders may use in their shoreline protection approaches. Results suggest that approaches that use natural materials tend to cost less than those that use more traditional, engineered materials, and nature-based approaches tend to cost somewhere in-between. Specifically, projects can be divided into four subgroups based on their average per-unit costs: (A) walls (mean: $5,628, se: $680) or stone at exposed sites (mean: $4,943, se: $725); (B) sand for beach nourishment (mean: $3,094, se: $397) or stone at low exposure sites ($3,014, se: $379); (C) stone and vegetation at low exposure sites (mean: $1,626, se: $217), stone and sand for other purposes at low exposure sites (mean: $1,411, se: $173), or sand for other purposes (mean: $1,384, se: $151); and (D) stone and sand for other purposes at low exposure sites (mean: $1,411, se: $173), sand for other purposes (mean: $1,384, se: $151), vegetation (mean: $1,300, se: $159), or vegetation and sand for other purposes (mean: $1,285, se: $172). Finally, monitoring and maintenance costs are often not accounted for, which may negatively affect the long-term success of shoreline protection efforts. Coupled with information on environmental and ecological effects of these different approaches, this information will allow for more informed decisions on how coastal and inland communities can best adapt to coastal risks.